In the conventional art, a two-needle sewing machine includes a bed part on which materials to be sewn such as a cloth, leather, and the like are placed, a column part erected upward from one side (right side) of the bed part, and an arm part provided to be substantially parallel to the bed part from an upper part of the column part. A needle shaft that reciprocates vertically by a driving motor (not illustrated) provided at a leading part (left part) of the arm part. Two sewing needles are mounted on the needle shaft. The bed part includes two horizontal hooks by which loops of needle threads of two sewing needles are caught, and a conveyor member conveying the materials to be sewn such as the cloth, the leather, and the like substantially in a direction orthogonal to the bed part.
The conventional two-needle sewing machine closely forms two stitches by two sewing needles. As illustrated in FIG. 26, two sewing needles 91 and 92 are arranged in a conveyance direction T of a material to be sewn 30 at a predetermined interval for the purpose of acquiring robust sewing, and a stitch 95A formed by a sewing needle 91 and a stitch 96A formed by a sewing needle 92 are brought into close contact to each other (for example, Patent document 1 and 2).